Finite Impulse Response (FIR) filters have been used in circuits in various fields such as digital communication, sound processing, and image processing. For example, in a field of digital communication, an emphasis optimization device that optimizes a setting value of an emphasis function to be added to an input digital signal is known (see Patent Document 1). Meanwhile, the emphasis function refers to a function of correcting a waveform in order to cancel the amount of deterioration of the waveform because the waveform may deteriorate due to frequency characteristics of a transmission line, a circuit, and the like in high-speed data communication.
The emphasis optimization device disclosed in Patent Document 1 includes inverse characteristic calculation means for calculating an inverse characteristic of an amplitude characteristic of a transmission line, inverse Fourier transform means for performing inverse Fourier transform on the inverse characteristic of the amplitude characteristic of the transmission line to obtain an optimal impulse response, impulse response cutout means for cutting out the number of taps necessary for an emphasis function from the impulse response, and optimal setting value calculation means for converting the cut-out impulse response into a value of an emphasis function to calculate an optimal setting value.
With such a configuration, the emphasis optimization device disclosed in Patent Document 1 can obtain an optimal setting value of an emphasis function without troublesome work.